1. Field of the Invention
The present invention relates to power management in a computer system, and more particularly to managing power among a group of servers in a rack-mounted computer system.
2. Background of the Related Art
A datacenter is a facility having one or more racks of computer equipment housed in a computer room for convenient access by datacenter personnel. The computer room provides a controlled environment and infrastructure conducive to operating the computer equipment. For example, a computer room may provide electrical utilities with the capacity to power a large volume of rack-mounted computer equipment, and a cooling system capable of removing the correspondingly large quantity of heat generated by the rack-mounted computer equipment. The cooling system in many installations will include a particular arrangement of equipment racks into alternating hot aisles and cold aisles, and a computer room air conditioner (“CRAC”) capable of maintaining a room temperature well below the temperature limits of the computer equipment.
Each rack may support one or more equipment chassis in a stacked relationship. For example, a rack mountable multi-server chassis typically includes multiple server bays having standardized dimensions, so that each server bay can receive a server of corresponding size. The server bays may be closely spaced and aligned to consolidate the servers in a compact, high-density arrangement. A multi-server chassis will also typically include support modules providing shared resources to the servers, such as a power supply module providing electrical power to the servers, a blower module for moving air through the servers, a network module providing network connectivity to the servers, and a supervisory controller for managing power and other chassis resources. Using support modules to provide shared resources allows the individual servers and the chassis receiving the servers to be made smaller and more compact.
Power management is a consideration in the design and development of computer systems. Continual efforts are made to improve the efficiency of today's computer systems. For example, a power cap for a server may be communicated to a server from an external agent, such as IBM Systems Director® (a registered trademark of International Business Machines Corporation of Armonk, N.Y.). The server then dynamically adjusts its power consumption to avoid exceeding the power cap, such as by throttling system components. Similar techniques can be applied to limiting the power consumption of a group of servers, such as a stand-alone rack of servers or blade servers in a shared chassis.